Phosphorylation of Mycobacterium tuberculosis FasR by PknB.

CABRUJA, M.; GRAMAJO, H; GAGO, G.

Canela

Congreso; VII Reunión de la Sociedad Latinoamericana de Tuberculosis y otras Micobacteriosis; 2014

SLAMTB

Background and objectives: Elucidation of mechanisms modulating fatty acid biosynthesis would shed light on the capacity of M. tuberculosis to adapt and survive within the infected host. Reversible protein phosphorylation is a key mechanism by which environmental signals are transmitted to cause changes in protein expression or activity in prokaryotes. Phosphorylation of proteins by Ser/Thr protein kinases (STPKs) has recently emerged as a major physiological mechanism of regulation in mycobacteria. FasR, is a key regulatory protein for maintaining lipid homeostasis in mycobacteria, as it modulates fatty acid availability by regulating the transcription of the fas gene. In this study, we investigated if phosphorylation of FasR might represent a strategy employed by M. tuberculosis to regulate fatty acid biosynthesis. Methods: In vitro phosphorylation experiments were performed using purified M. tuberculosis FasR, PknA and PknB. Results and discussion: We show that FasR is efficiently phosphorylated in vitro by several mycobacterial STPKs, particularly by PknB. The identification of the main phosphoacceptors using mass spectrometry analyses will allow us to investigate if phosphorylation of FasR by PknB modulates its biochemical activity. Conclusion: Fatty acids are used for the biosynthesis of essential lipids of mycobacteria membrane (phospholipids and mycolic acids) and also for triacylglycerol biosynthesis, the storage lipids that accumulates during the intracellular growth of M. tuberculosis. The involvement of STPKs in modulating FasR activity broaden the intricacies of mycobacterial signaling networks in order to adapt lipid composition to the changing environment.